The past tense of leave a sour taste in one's mouth is left a sour taste in one's mouth.
The third-person singular simple present indicative form of leave a sour taste in one's mouth is leaves a sour taste in one's mouth.
The present participle of leave a sour taste in one's mouth is leaving a sour taste in one's mouth.
The past participle of leave a sour taste in one's mouth is left a sour taste in one's mouth.